applications of phosphorus on soils low in this element has been well demonstrated by the farmers of Livingston County, Ill. In this county finely ground rock phosphate was applied to a portion of a number of fields at the rate of 1,500 to 2,000 pounds per acre. The phosphate was thoroughly incorporated with the soil just before seeding oats and sweet clover. In the growth of sweet clover there was a marked difference the following year between the treated and untreated portions of the fields. Those portions of the fields which received an application of phosphate not only contained many more plants on a given area, but the vigor and growth of the plants were most marked. On June 1 the plants on the treated areas were 12 to 15 inches taller than those on the untreated parts of the fields. This difference in the thickness of stand and the height of plants was so striking that the last round of the phosphate spreader was plainly distinguishable.

Yields of sweet-clover hay have been increased as much as 2 tons per acre from applications of barnyard manure. Such an increased yield would be equal approximately to 8 tons of green-manure. Some people may consider it poor farm practice to apply manure to such crops as sweet clover, but it is very probable that the cumulative effect of the increased yields of the following crops, especially on soils low in organic matter, will be greater than if the manure is applied to other crops. Heavy applications of manure to the preceding crop should also greatly benefit sweet clover.

USE OF A NURSE CROP.

If sweet clover is to become an important crop throughout the North-Central States it must necessarily be seeded with grain. Good success has been obtained by seeding sweet clover in the spring on winter grain or with spring grain on soil that was inoculated and not acid. Seed may be broadcasted in the early spring on winter grain when the ground is in a honeycombed condition, or it may be sown later when the ground may be cultivated. A large acreage of sweet clover is sown in the western North-Central States and in Illinois in the spring with oats, barley, or wheat as a nurse crop. Early varieties of oats and spring wheat have given somewhat better results in portions of the Northwest than barley. In Illinois oats are used almost entirely. Only a few fields were noted where flax had been used as a nurse crop, but in these fields it was successful. In wet seasons the sweet clover may make a growth sufficiently large to interfere seriously with harvesting the flax. On this account this combination should be tested thoroughly in an experimental way before being recommended for general field practice.

In those sections of the country where the moisture supply is limited, sweet clover should be sown without a nurse crop. Failure to obtain a stand is more likely to occur when the seed is sown with grain than when it is sown alone, because during dry weather, which is likely to occur when the grain is maturing, the supply of moisture in the soil is apt to be insufficient for both crops. When this condition prevails the clover will suffer badly and in some cases be killed. When sweet clover is sown with a nurse crop it is strongly recommended that the grain be seeded at not more than two-thirds the usual rate. This will give the sweet clover a much better chance than when a full seeding is made. When severe droughts occur it may be necessary to cut the grain for hay if the stand is to be saved.

CHOICE OF SEED.

On account of the low germination of much of the sweet-clover seed offered for sale it is very important that seed be tested for germination before planting. Low germination usually is due to the fact that many of the seeds remain hard after they have been in the germinator or soil for a month or more. The seed coats of hard sweet-clover seeds become permeable to water very slowly, if at all, in storage. The germination of such seeds is greatly increased, however, when they are subjected for a time to alternating temperatures, such as freezing and thawing. It is on this account that unhulled seed, which germinates poorly in the laboratory, often will produce good stands when sown during the winter. When sweet clover is to be sown in the spring it is very important that only hulled seed which germinates 75 per cent or more be sown. As explained later under the heading "Seeding," unhulled seed which has a low germination should be used for seeding only during the winter months, so that there will be sufficient time for the alternating temperatures of winter and early spring to cause it to germinate during favorable weather.

Hulled seed usually germinates much better than unhulled seed, as is shown in Table I.

Table I.—Germination and hard seed content of samples of sweet-clover seed, hulled, and unhulled, from different sources.

Table I shows that northern-grown seed germinates better than northern-grown seed and imported seed better than either. The low germination of the southern-grown seed is probably due to the fact that a very large percentage of it is flailed out and sown in the hull. Northern-grown seed generally is thrashed with either a grain separator or a clover huller. Imported seed always is hulled. In hulling seed the rasps or concaves of the machines scratch the seed coats sufficiently to permit water to penetrate them, so that the germination is greatly increased. Apparently there is no reason why southern-grown seed when it is properly hulled should not germinate as well as northern-grown seed.

Since the Ames scarifying machine (fig. 8)[7] has been placed on the market, it is possible to buy scarified seed. This machine is so constructed that the seed is forced through a conveyor, part of which is covered with sandpaper. When the seed comes in contact with the sandpaper it is scratched, so that water will penetrate the seed coats. When this machine is run properly the germination of seed is greatly increased, but when carelessly operated germination may be lessened, as many of the seeds may be broken.